RFID tags are wireless non-contact devices that transmit an identifying signal to a receiver. Such tags are used in many industries. RFID tags may be attached to devices for inventory purposes. These tags may be used for protection against theft. A receiver located at a store entrance may receive signals from RFID devices as they are being transported out of the store, for example. Maintenance status can be monitored using RFID tags. For example, a user can query a device having an RFID tag. The received identifying signal can be used to look up the maintenance status of the queried device, for example. Manufacturing lines may use RFID tags to track parts being assembled into production units. For example, an assembly machine may query the product as to what revision of boards it may contain. In response to the board identification, the assembly machine may select a part that corresponds to the revision of the device being manufactured. RFID tags have been inserted into access control cards. Such cards permit or deny access to individuals according to predetermined rules of permission.